1. Field of the Invention
The present invention is in the technical field of component separation. More specifically, the present invention is in the technical field of chromatography separation using a simulated moving bed of stationary phase where the fluid in the stationary phase flows in the radial direction.
2. Description of the Prior Art
Conventional chromatography separates molecules by passing sample vertically down an axial column in the batch mode. A continuous chromatography system that has high throughput and requires less solvent was described by Broughton et al in U.S. Pat. No. 2,985,589 with a simulated moving bed (SMB). The adsorption and desorption continuously take place which allows both continuous production of an extract, a raffinate stream, injection of the feed and desorbent streams. The upward movement of the adsorbent is simulated by progressive movement of the feed, desorbent, extract and raffinate access points down an adsorbent chamber. The liquid movement in the adsorbent chamber is provided by a circulation pump. Access points on the adsorbent chamber divide the chamber into separate zones. Each zone can have multiple adsorbent beds and the liquid in the cylindrical adsorbent bed moves in the axial direction.
In order to minimize the flow rate variation and channeling in the short adsorbent bed, a fluid distribution device is provided at each access point on the adsorbent chamber. A wide variety of means to introduce and withdraw fluid stream from the chamber can be used and found in U.S. Pat. Nos. 3,214,247, 3,789,989, 4,378,292, 6,024,871 and 7,314,552 B2. The fluid distribution device combines mixing, flow distribution and collecting functions. It needs to prevent backmixing and has a low dead volume and a low pressure drop. As many adsorbent beds are needed for the component separation, many fluid distributors are required.
The adsorbent chamber is packed with separation material in each bed. When a larger scale separation is required, the volume required for separation material and process flow rate are increased to meet the production rate requirement. The combination of the increase of flow rate, larger bed height and compression stress in the packing material bed leads to a high pressure drop across the packing bed. Rigid packing or large size packing material in the bed can reduce the pressure drop but results in inferior process performance.
The progressive movement of the feed, desorbent, extract and raffinate to the adsorbent chamber access points in cyclic manner is accomplished by utilizing a manifold system in which the valves in the manifold are sequentially operated. Alternately, a rotating disc valve with input and output streams connected to the access points of the adsorbent chamber can be found in prior art to replace the aforementioned valved manifold system. U.S. Pat. No. 3,040,777 to Carson et al and 3,422,848 to Liebman are the two early examples. Significant efforts have been made to the design of the rotary valve as in U.S. Pat. Nos. 4,935,464, 5,268,021, 5,366,541, 5,779,771, 5,820,656, 6,457,485, 7,544,293. The rotary valve still requires many inlet/outlet lines to communicate input and outputs streams to the access points of the adsorbent bed on the vessel.
The United States Patent Application Publication No. US 2010/0329949 A1 shows a radial flow continuous reaction/regeneration apparatus. This apparatus uses a rotary device to distribute the process feed and regeneration fluid annularly into a stationary segmented reaction/regeneration box and receiving effluents individually and annularly from the same stationary reaction/regeneration box. The flow in the segmented box is in radial direction. The radial flow continuous reaction/regeneration apparatus can be operated continuously and efficiently without the need for shutting down for regeneration. Although this device neither needs the valved manifold system nor a rotating disc valve with many input/output lines, the filler in the annular fan segment cannot move with or against the flowing fluid in the segment. It cannot be used as moving bed and the simulated moving bed has known advantages and higher efficiency over the batch system with continuous swing bed operation.
It is therefore the object of this invention to provide a Simulated Moving Bed Chromatography device to perform the continuous unattended separation of components with consistent product quality as the conventional SMB system without the need for adding more fluid distributor/collector when the number of physical separation stage increases. The new device with a mobile phase moving in radial direction combines the advantages for radial flow and rotary valve without the need to rotate the annular packed stationary phase bed. The short radial flow bed reduces the bed stress developed due to the axial flow compression and decreases pressure drop and in turn allow greater throughput and the use of more efficient soft stationary phase packing. Instead of increasing the bed height and diameter in the axial flow column, the radial flow device can increase the module height and gives higher capacity. The scaling up process is thus simpler. In order to improve the separation efficiency of the radial flow continuous reaction/regeneration apparatus described in US 2010/0329949 A1, a fluid moving device is added and the partition plate in various segments are improved with added channels or added by passes to connect adjacent segments. The stationary and fluid phases can therefore move relative to each other. The continuous reaction/regeneration apparatus or a continuous chromatography system can thus turn into a simulated moving bed chromatography device and the desorbent uses and the adsorbent loading can be reduced.